Vessel Parameters Research Articles

Retinal vessel flicker light responsitiviness and its relation to analysis protocols, static and metabolic data in healthy subjects

Aims/Purpose: To assess agreement between different analysis protocols for determination of retinal vessel dilation response to flicker light (FL) and its relation to static‐ and metabolic parameters of retinal vessels in healthy subjects.Methods: 24 right eyes of 24 healthy controls (mean age: 35.87 ±SD 14.20 years), who underwent dynamic‐ and static retinal diameter‐ and oxygen saturation measurements on Retinal Vessel Analyser were included (RVA, Imedos, Jena, Germany). Using repeated video analyses, responses to FL were measured within the superior‐temporal (ST) area. Taking the length and the location into account, the FL data were evaluated in 3 groups: length < 1 optic disc (OD) (group 1); length > 1OD: close to the OD (group 2) and within the VesselMap area (group 3).For comparability, the static‐ (CRA, CRV, AVR) and oxygen saturation parameters (A‐V SO2, V‐SO2, A‐V SO2) were calculated in the ST peripapillary area using the VesselMap tool of RVA and were evaluated in relation to the corresponding dynamic ones (group 3).Results: In all groups, vascular FL response of arteries was less pronounced compared to venules (p = 0.023). Event thought, FL responses (mean ±SD: FL‐A; FL‐V, %) in group 1 to be more pronounced (mean 3.36 ±2.31; 4.42 ±1.69) compared to those in groups 2 (mean: 2.97 ±2.40; 4.08 ±1.55) and 3 (2.84 ±2.29; 4.21± 2.03) they did not reach statistically significant values (p > 0.44).The mean flicker response of venules showed negative correlations to the corresponding static‐ and metabolic parameters: CRV (r = ‐0.489; p = 0.015) and V‐SO2 (r = ‐0.375; p = 0.001).Conclusions: Our study confirms, that flicker light response, even showing slight difference about its length and location, allows agreeable measurements. However, even in healthy subjects, the effect of the static‐ and metabolic retinal vessel measurements on retinal venular flicker response should be taken in consideration.

Retinal vessel flicker light responsitiviness and its relation to analysis protocols, static and metabolic data in healthy subjects

Aims/Purpose: To assess agreement between different analysis protocols for determination of retinal vessel dilation response to flicker light (FL) and its relation to static‐ and metabolic parameters of retinal vessels in healthy subjects.Methods: 24 right eyes of 24 healthy controls (mean age: 35.87 ± SD 14.20 years), who underwent dynamic‐ and static retinal diameter‐ and oxygen saturation measurements on Retinal Vessel Analyser were included (RVA, Imedos, Jena, Germany). Using repeated video analyses, responses to FL were measured within the superior‐temporal (ST) area. Taking the length and the location into account, the FL data were evaluated in 3 groups: length < 1 optic disc (OD) (group 1); length > 1OD: close to the OD (group 2) and within the VesselMap area (group 3).For comparability, the static‐ (CRA, CRV, AVR) and oxygen saturation parameters (A‐V SO2, V‐SO2, A‐V SO2) were calculated in the ST peripapillary area using the VesselMap tool of RVA and were evaluated in relation to the corresponding dynamic ones (group 3).Results: In all groups, vascular FL response of arteries was less pronounced compared to venules (p = 0.023). Event thought, FL responses (mean ± SD: FL‐A; FL‐V, %) in group 1 to be more pronounced (mean 3.36 ± 2.31; 4.42 ± 1.69) compared to those in groups 2 (mean: 2.97 ± 2.40; 4.08 ± 1.55) and 3 (2.84 ± 2.29; 4.21 ± 2.03) they did not reach statistically significant values (p > 0.44).The mean flicker response of venules showed negative correlations to the corresponding static‐ and metabolic parameters: CRV (r = ‐0.489; p = 0.015) and V‐SO2 (r = ‐0.375; p = 0.001).Conclusions: Our study confirms, that flicker light response, even showing slight difference about its length and location, allows agreeable measurements. However, even in healthy subjects, the effect of the static‐ and metabolic retinal vessel measurements on retinal venular flicker response should be taken in consideration.

Comparing the Doppler flow parameters of orbital vessels among healthy nonsmokers, diabetic nonsmokers, and diabetic smokers visiting a tertiary health-care center.

The present study aimed to assess the impact of diabetes mellitus and smoking in orbital vessels, utilizing resistive index (RI) through color Doppler imaging (CDI). The cross-sectional study consisted of 90 participants divided into three groups of 30 each. Group A consisted of normal individuals, Group B consisted of patients with diabetes, and Group C consisted of patients with a history of diabetes and smoking. The RIs were obtained for the orbital vessels for both eyes using CDI. Analysis of variance with post hoc Tukey's HSD test was conducted for pairwise comparison of the groups. Pearson's correlation test was used to correlate between RI and the amount of smoking. Significant differences were observed in the mean RI values of the ophthalmic artery, central retinal artery (CRA), and central retinal vein (CRV) in all three groups bilaterally (P < 0.001). Compared with patients in Group A, those in Group B had significantly larger RIs for all orbital vessels in both eyes (P < 0.01 for all). Patients in Group C had significantly larger RI for all three vessels (P < 0.001 for all) except for the CRV in the right eye than those in Group A. Compared with patients in Group B, those in Group C had significantly larger RI in CRA bilaterally (P = 0.05 for the right eyes and P = 0.024 for the left eyes). In Group C, a positive correlation was observed between RIs of all orbital vessels and the amount of smoking. RIs of the orbital vessels are significantly increased in patients with diabetes and higher in diabetic smokers, suggesting that diabetes affects the retinal vasculature, and smoking exacerbates this pathology.

Optical properties, thermal conductivity, and viscosity of graphene-based nanofluids for solar collectors

Nanofluids based on graphene and water are promising working fluids for use in solar collectors. In this study, the optical properties, thermal conductivity, and viscosity of nanofluids based on water and graphene material, with the addition of sodium dodecyl sulfate (SDS) surfactant, were experimentally investigated. To obtain these nanofluids, graphene nanoparticles were synthesized using a plasma-chemical method and were later characterized by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The relationships between the concentrations of graphene in the nanofluids and the geometric parameters of vessels for effective absorption of solar energy were determined. The spectral dependences of the extinction coefficient for the nanofluids and for aqueous solutions with black aniline dye were compared. It was found that the application of graphene-based nanofluids is more effective than aqueous solutions based on aniline dye in photothermal energy conversion. Additionally, it was noted that the addition of graphene and the SDS surfactant does not lead to an increase in viscosity or a significant change in the thermal conductivity of the nanofluids for concentrations up to 0.02 wt%. The results showed that the studied nanofluids are effective absorbers of solar energy and, at the same time, do not require additional energy consumption to move through the solar harvesting circuit.

Acute effects of high-intensity interval training on microvascular circulation: a case control study in uveal melanoma

Abstract Objectives The aim of this study was to explore the acute effects of high-intensity interval training (HIIT) on the microvascular circulation and vascular tumor microenvironment (TME) in a patient with uveal melanoma (UM). Additionally, the acceptance of the applied diagnostics and the exercise protocol in a clinical ophthalmic-oncology setting were evaluated. Methods This case-control study included a young adult male patient with UM previously treated with radiation and an age-matched healthy control. Participants underwent a baseline assessment of dynamic retinal vessel analysis (DRVA) and cardiopulmonary exercise testing (CPET) to determine endothelial function and intensity for HIIT. Optical coherences tomography angiography (OCTA) was performed before, immediately and 30 min after one session of HIIT. The primary outcome were changes in ocular vessel parameters and whole body oxygen uptake. Results The UM patient exhibited lower arterial dilation and constriction in the affected eye compared to his healthy eye and both eyes of the healthy control. OCTA revealed heterogeneous patterns of vascular response to HIIT in both participants. The tumor eye showed an increase followed by a significant decrease in vessel density post-exercise, while the healthy control exhibited minor increases. Conclusions The findings of this study highlighted the potential of UM combined with OCTA and DRVA as a model for examine exercise-induced vascular effects within the TME. However, a pre-treated UM as well as detailed image analyses and further research with longitudinal, randomized controlled designs are essential to validate these findings and address methodological limitations. Such investigations could refine integrative cancer treatment.

Изучение динамики регионарного кровотока и микрокровотока макулы в зависимости от проводимого лечения у пациентов с хронической ишемической ретинопатией, ассоциированной с гемодинамически значимым атеросклеротическим стенозом внутренней сонной артерии

Purpose. To evaluate dynamics of regional blood flow and microcirculation of macula depending on treatment in patients with chronic ischemic retinopathy (CIR) associated with hemodynamically significant atherosclerotic stenosis of internal carotid artery (ICA). Material and methods. This study included 92 patients (92 eyes) with a severe degree of CIR. Patients were divided into 3 groups according to the type of performed treatment. The 1st group – 32 patients (32 eyes) who underwent only carotid endarterectomy (CEA) of the ICA. The 2nd group consisted of 30 patients (30 eyes), where only panretinal laser coagulation of the retina (PRLC) was performed. The 3rd group included 30 patients (30 eyes), who first underwent PRLC of retinal nonperfusion zones, then after 2 weeks – CEA of the ICA. Results. CEA of the ICA in patients with hemodynamically significant atherosclerotic stenosis improves hemodynamic parameters of the eye vessels. CEA of the ICA as a method of CIR treatment allows restoring microcirculation in the macula by 6th month of observation, in 22% of cases it leads to the development of reperfusion in retinal structures. After PRLC, progression of retinopathy was observed in 76% of patients and it led to a slight improvement in macula microcirculation. A session of PRLC in combination with CEA of the ICA made it possible to reduce the period of restoration of macula microcirculation to 3 months and to reduce the frequency of reperfusion processes to 6%. Conclusion. The use of PRLC with CEA of the ICA in patients with 3 grade CIR associated with hemodynamically significant stenosis of the ICA allowed to make significant improvement in macular microcirculation and to decrease the frequency of reperfusion symptoms in patients by 3,5 times. Key words: ocular ischemic syndrome, chronic ischemic retinopathy, macula microcirculation, hemodynamics, carotid endarterectomy, panretinal laser coagulation, internal carotid artery

Bedside 3D ultrasound fistula maturation assessment by non-expert sonographers provides equivalent accuracy to formal duplex sonography: A prospective clinical trial.

EchoSure is an automated point-of-care 3D ultrasound (3DUS) designed to be used by dialysis technicians without advanced ultrasound training. The EchoMark/EchoSure System is a two-part system comprised of a bioresorbable implant, EchoMark, and a diagnostic ultrasound imaging platform, EchoSure. EchoSure was designed to enable any healthcare personnel in a dialysis clinic setting to obtain non-invasive, direct measurements of flow and vessel parameters that are critical quantifications used in the assessment of AVF maturation and readiness for hemodialysis cannulation. In this pilot feasibility study, we sought to explore whether use of an automated 3DUS could enable fistula assessment by non-experts and obtain measurement accuracy comparable to expert sonographer Duplex. This was a 20 subject prospective multicenter trial conducted at four sites in the United States. All subjects had an EchoMark implanted under their AVF during the fistula creation procedure. Subjects were evaluated at 2-weeks post-op with EchoSure and Duplex, followed by monthly assessments until either the 4-month visit or until radiographic maturation was achieved, whichever was longer. Beyond monthly ultrasound assessments, clinical follow-up continued every 6 months between months 6 and 24. Technical success of EchoMark implantation was demonstrated in 100% of subjects. Technical success of EchoSure was 99% across all scans. The mean percent difference in flow rate measurements between EchoSure and Duplex was -9.2% with a standard deviation of 38.1% compared to a mean percent difference of -15.7% with a standard deviation of 35.5% between Duplex measurements taken at the cannulation zone and brachial artery. Pearson correlation between EchoSure and Duplex was 0.708 versus 0.716 for the two Duplex measurements. Radiographic maturation was achieved in 70% of study subjects by 30 days and continued to rise to 90% through 90 days and 95% through 180 days after baseline. This study demonstrates the feasibility and accuracy of an automated 3D ultrasound system for assessment of maturation at the dialysis bedside by non sonographers.

Vessel Geometry Estimation for Patients with Peripheral Artery Disease

The estimation of vessels’ centerlines is a critical step in assessing the geometry of the vessel, the topological representation of the vessel tree, and vascular network visualization. In this research, we present a novel method for obtaining geometric parameters from peripheral arteries in 3D medical binary volumes. Our approach focuses on centerline extraction, which yields smooth and robust results. The procedure starts with a segmented 3D binary volume, from which a distance map is generated using the Euclidean distance transform. Subsequently, a skeleton is extracted, and seed points and endpoints are identified. A search methodology is used to derive the best path on the skeletonized 3D binary array while tracking from the goal points to the seed point. We use the distance transform to calculate the distance between voxels and the nearest vessel surface, while also addressing bifurcations when vessels divide into multiple branches. The proposed method was evaluated on 22 real cases and 10 synthetically generated vessels. We compared our method to different state-of-the-art approaches and demonstrated its better performance. The proposed method achieved an average error of 1.382 mm with real patient data and 0.571 mm with synthetic data, both of which are lower than the errors obtained by other state-of-the-art methodologies. This extraction of the centerline facilitates the estimation of multiple geometric parameters of vessels, including radius, curvature, and length.

The calculation method of blood flow pressure based on four-dimensional flow magnetic resonance imaging and deep learning

Utilizing artificial intelligence methods for blood flow pressure estimation can significantly enhance the computational speed of blood flow pressure. However, current related research can only calculate the blood flow pressure parameters of vessels with different geometric shapes under fixed boundary conditions, thus fail to achieve transient flow field calculation and consider the hemodynamic differences formed by patients' varying physiological and pathological conditions. In view of this, this study proposes a method for relative pressure estimation based on four-dimensional flow magnetic resonance imaging (4D flow MRI) of patient blood flow and deep learning. 4D flow MRI was used to obtain the patient's blood flow velocity gradient data, and feature engineering processing is performed on the sampled data. Then, a novel neural network was proposed to acquire the characteristic relationship between velocity gradient and pressure gradient in the vicinity of the point to be measured and within adjacent sampling time periods, thereby achieving the calculation of the relative pressure in the vicinity of the point to be measured. Statistical analysis was performed to evaluate the efficacy of the method, comparing it with computational fluid dynamics methods and catheter pressure measurement techniques. The accuracy of the proposed method exceeded 96%, while computational efficiency was improved by several tens of times, and no manual setting of physiological parameters was required. Furthermore, the results were compared with clinical catheter-measured pressure results, r2 = 0.9053, indicating a significant consistency between the two methods. Compared to previous research, the method proposed in this study can take the blood flow velocity conditions of different patients at different times as input features via 4D flow MRI, thus enabling the calculation of pressure in transient flow fields, which significantly improved computational efficiency and reduced costs while maintaining a high level of calculation accuracy. This provides new direction for future research on machine learning prediction of blood flow pressure.

The role of light intensity in water transport and homeostasis across different vapor pressure deficit conditions

Vapor pressure deficit (VPD) directly affects the driving force of plant water movement by altering the water potential gradient between the atmosphere and plants and indirectly influences the resistance to water movement by regulating plant structure. Concurrently, light intensity modulates both the driving force and resistance to water movement by regulating plant morphology and nonstructural carbohydrate synthesis. Despite significant advances in the understanding of the regulatory effects of VPD on water absorption and transport in tomatoes, the effect of light intensity regulation under varying VPDs on water transport and homeostasis remains to be clarified. Here, we investigated the effects of two light intensities (L300; 300 µmol m–2 s–1, L600; 600 µmol m–2 s–1) on plant anatomy, physiological traits, hydraulic properties, and expression of plasma membrane intrinsic proteins (PIPs) and tonoplast intrinsic proteins (TIPs) in tomatoes subjected to long-term high and low VPDs. In addition, we analysed the correlations and path coefficients of these indicators. These results indicate that higher light intensity reduces resistance to water movement by enhancing root morphology, vessel parameters in roots and stems, leaf vein density, stomatal morphology, physiological traits, and expression of SlTIPs and SlPIPs in both roots and leaves. Concurrently, increased light intensity boosts the driving force of water movement by amplifying the water potential difference and transpiration under low VPD. However, under high VPD, elevated light intensities create a larger water potential difference, prompting plants to reduce this excessive force by decreasing transpiration and stomatal conductance, thereby maintaining water homeostasis. These findings suggest that light intensity can effectively regulate water homeostasis by dynamically optimising plant structure, hydraulic properties, and the expression of SlTIPs and SlPIPs across different VPDs, providing a theoretical foundation for practical light intensity management in agriculture.

Unenhanced computed tomography as a diagnostic tool in suspected pulmonary hypertension: a retrospective cross-sectional pilot study.

Computed tomography pulmonary angiography (CTPA) has been proposed to be diagnostic for pulmonary hypertension (PH) in multiple studies. However, the utility of the unenhanced CT measurements diagnosing PH has not been fully assessed. This study aimed to assess the diagnostic utility and reproducibility of cardiac and great vessel parameters on unenhanced computed tomography (CT) in suspected pulmonary hypertension (PH). In total, 42 patients with suspected PH who underwent unenhanced CT thorax and right heart catheterization (RHC) were included in the study. Three observers (a consultant radiologist, a specialist registrar in radiology, and a medical student) measured the parameters by using unenhanced CT. Diagnostic accuracy of the parameters was assessed by area under the receiver operating characteristic curve (AUC). Inter-observer variability between the consultant radiologist (primary observer) and the two secondary observers was determined by intra-class correlation analysis (ICC). Overall, 35 patients were diagnosed with PH by RHC while 7 patients were not. Main pulmonary arterial (MPA) diameter was the strongest (AUC 0.79 to 0.87) and the most reproducible great vessel parameter. ICC comparing the MPA diameter measurement of the consultant radiologist to the specialist registrar's and the medical student's were 0.96 and 0.92, respectively. Right atrial area was the cardiac measurement with highest accuracy and reproducibility (AUC 0.76 to 0.79; ICC 0.980, 0.950) followed by tricuspid annulus diameter (AUC 0.76 to 0.79; ICC 0.790, 0.800). MPA diameter and right atrial areas showed high reproducibility. Diagnostic accuracies of these were within the range of acceptable to excellent, and might have clinical value. Tricuspid annular diameter was less reliable and less diagnostic and was therefore not a recommended diagnostic measurement.

Trajectory Tracking Control of an Autonomous Vessel in the Presence of Unknown Dynamics and Disturbances

We present a proportional–integral–derivative-based controller plus an adaptive slide surface to solve the trajectory tracking control problem for a fully actuated vessel with unknown parameters perturbed by slowly varying external unknown dynamics. The controller design assumes that the vessel moves at low speed and frequency, its physical parameters are unknown, and its state is measurable. The control approach ensures error tracking convergence toward a small vicinity at the origin. We conduct the corresponding stability analysis using the Lyapunov theory and saturation functions. We tested the controller through two numerical experiments—a turning ellipse maneuver and a rest-to-rest maneuver—where the vessel parameters were unknown, and we obtained satisfactory results.

Deep Learning‐Enabled Vasculometry Depicts Phased Lesion Patterns in High Myopia Progression

PurposeTo investigate the potential phases in myopic retinal vascular alterations for further elucidating the mechanisms underlying the progression of high myopia (HM). MethodsFor this retrospective study, participants diagnosed with high myopia at Beijing Tongren Hospital were recruited. Based on bionic mechanisms of human vision, an intelligent image processing model was developed and utilized to extract and quantify the morphological characteristics of retinal vasculatures in different regions measured by papilla-diameter (PD), including vascular caliber, arteriole-to-venule ratio (AVR), tortuosity, the angle of the vascular arch (AVA), the distance of the vascular arch (DVA), density, fractal dimension, and venular length. In addition, the optic disc and the area of peripapillary atrophy (PPA) were also quantified. The characteristics of the overall population, as well as patients aged less than 25 years old, were compared by different genders. Univariate and multiple linear regression analyses were conducted to investigate the correlation of retinal vasculature parameters with PPA width, and detailed trends of the vascular indicators were analyzed to explore the potential existence of staged morphological changes. FindingsThe study included 14,066 fundus photographs of 5775 patients (aged 41.2 ± 18.6 years), of whom 7379 (61.2 %) were female. The study included 12,067 fundus photographs of 5320 patients (aged 41.2 ± 18.6 years). Significant variations in the morphological parameters of retinal vessels were observed between males and females. After adjusting for age and sex, multiple linear regression analysis showed that an increased PPA width ratio was associated with lower AVA (1PD), DVA (1PD), vascular caliber (0.5–1.0 PD), tortuosity (0.5–1.0 PD), density and fractal dimension (all P < 0.001, Spearman’s ρ < 0). Overall, the changes in retinal vascular morphology showed two phases: tortuosity (0.5–1.0PD) and AVA (1PD) decreased rapidly in the first stage but significantly more slowly in the second stage, while vascular density and fractal dimension showed a completely opposite trend with an initial slow decline followed by a rapid decrease. ConclusionsThis study identified two distinct phases of retinal vascular morphological changes during the progression of HM. Traction lesions were predominant in the initial stage, while atrophic lesions were predominant in the later stage. These findings provide further insight into the development mechanism of HM from the perspective of retinal vasculature.

Opportunistic ship source level measurements in the Western Canadian Arctica).

Increased ship traffic due to climate change increases underwater noise in the Arctic. Therefore, accurate measurements of underwater radiated noise are necessary to map marine sound and quantify shipping's impact on the Arctic ecosystem. This paper presents a method to calculate opportunistic source levels (SLs) using passive acoustic data collected at six locations in the Western Canadian Arctic from 2018 to 2022. Based on Automatic Identification System data, acoustic data, and a hybrid sound propagation model, the SLs of individual ships were calculated within a 5 km radius of each measurement site. A total of 66 measurements were obtained from 11 unique vessels, with multiple measurements from the same vessel type contributing more SLs. For vessels with propeller cavitation, measured SLs correlated positively with vessel parameters, such as speed and length. SL and speed did not correlate well for vessels without propeller cavitation. The JOMOPANS-ECHO SL model produced good agreement with measured SL for certain ship types (container ships, a tanker, and a passenger vessel). However, significant differences between measurement and model are evident for certain polar-class ships that travel in the Arctic, indicating that more controlled SL measurements are needed.

Beyond Jack-Ups: A Moonshot for Future Offshore Wind Turbine Installation Vessels for an Uncertain Market

This paper addresses the growing offshore wind market's demand for larger turbines in deeper waters by highlighting limitations in existing installation solutions and proposing a new concept with a floating monohull, named Moonshot, which will thus be different than traditional jack-up or semi-submersible crane installation vessel options. This paper discusses the design process, which combines Ulstein Rotterdam’s Controlled Innovation and Blended Design to develop the concept. This process is used to explore various market scenarios to determine optimal vessel parameters. Results demonstrate how optimizing for financial performance or seakeeping behavior impacts the design. Moonshot's initial parameters are established, and its performance is compared to existing installation solutions.

Distributed Robust Learning-Based Backstepping Control Aided With Neurodynamics for Consensus Formation Tracking of Underwater Vessels.

This article addresses distributed robust learning-based control for consensus formation tracking of multiple underwater vessels, in which the system parameters of the marine vessels are assumed to be entirely unknown and subject to the modeling mismatch, oceanic disturbances, and noises. Toward this end, graph theory is used to allow us to synthesize the distributed controller with a stability guarantee. Due to the fact that the parameter uncertainties only arise in the vessels' dynamic model, the backstepping control technique is then employed. Subsequently, to overcome the difficulties in handling time-varying and unknown systems, an online learning procedure is developed in the proposed distributed formation control protocol. Moreover, modeling errors, environmental disturbances, and measurement noises are considered and tackled by introducing a neurodynamics model in the controller design to obtain a robust solution. Then, the stability analysis of the overall closed-loop system under the proposed scheme is provided to ensure the robust adaptive performance at the theoretical level. Finally, extensive simulation experiments are conducted to further verify the efficacy of the presented distributed control protocol.

Spatiotemporal analysis of the effects of exercise on the hemodynamics of the aorta in hypertensive rats using fluid-structure interaction simulation.

Hemodynamic changes that lead to increased blood pressure represent the main drivers of organ damage in hypertension. Prolonged increases to blood pressure can lead to vascular remodeling, which also affects vascular hemodynamics during the pathogenesis of hypertension. Exercise is beneficial for relieving hypertension, however the mechanistic link between exercise training and how it influences hemodynamics in the context of hypertension is not well understood. n exercise model was developed using spontaneously hypertensive rats (SHR) subject to a 12-week treadmill training regime. The heart rates and blood pressures of rats were measured using the tail cuff method, while micro-computed tomography (CT) scanning was used to develop three-dimensional structures of rat aorta, and ultrasound was used to detect rat aortic blood flow and changes to vessel wall structures. Computational fluid dynamics (CFD) and fluid-structure interaction (FSI) models were used to simulate and measure hemodynamic parameters of the rat aortic vessels. In parallel, Masson staining was performed on fixed samples of blood vessels to investigate collagen volume fraction. Hypertensive rats in the sedentary and long-term exercise training groups were subjected to a single bout exercise training, and their aortic hemodynamic parameters were analyzed before, 5 min, 24 h, and 72 h after the single bout exercise. Of the two models, in comparison to actual ultrasonic measurement values recorded, we found that numerical simulation results from the FSI model could more accurately model blood flow in the ascending aorta of hypertensive rats, compared to the CFD model. Moreover, longterm exercise training improved local hemodynamic parameters of blood vessels, and led to improvements in adverse hemodynamic features documented, including time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT). Longterm exercise training of SHR also improved local vascular collagen deposition in the aorta, while improvements in vascular remodeling were also correlated with favorable hemodynamic parameters. Compared with sedentary SHR, signals for low TAWSS regions of the aortic arch in SHR on the long-term exercise regime shifted to the position of the ascending aorta after a single bout of exercise. This study demonstrates that FSI is informative to study the spatiotemporal effects of long-term exercise training on hemodynamic changes within the aortas of hypertensive rats, and that long-term exercise is beneficial through its effects to modulate vascular hemodynamics in hypertension.

Retinal artery to vein ratio is associated with cerebral microbleeds in individuals with type 1 diabetes.

A third of asymptomatic individuals with type 1 diabetes (T1D) show signs of cerebrovascular disease in brain MRI. These signs associate with advanced stages of diabetic retinal disease, but not in mild or moderate retinopathy. We aimed to evaluate a wider spectrum of retinal changes by exploring the relationship between quantitative measures of retinal vessel parameters (RVP) and cerebrovascular changes in T1D. We included 146 neurologically asymptomatic individuals with T1D [51% women, median age 40 (33.0-45.1) years] and 24 healthy, sex-matched and age-matched controls. All individuals underwent a clinical and biochemical work-up and brain MRI, which was evaluated for cerebral microbleeds (CMBs), white matter hyperintensities, and lacunar infarcts. RVPs, including central retinal arteriole (CRAE) and central retinal vein (CRVE) equivalents and the ratio of the two variables (arteriovenous ratio, AVR) were assessed quantitatively by a computer-assisted method (IVAN software, version 3.2.6) from fundus images. Among T1D participants, those with CMBs had a lower arteriovenous ratio (AVR) compared with those without CMBs ( P = 0.023). AVR was inversely associated with the amount of CMBs ( r = -0.063, P = 0.035). CMB prevalence was higher in those with AVR below the median (31%) compared with above the median (16%, P < 0.001), and this difference was significant also after individuals with only no-to-mild retinopathy were included (28 vs. 16%, P = 0.005). A correlation between blood pressure and CRAE ( r = -0.19, P = 0.025) appeared among those with T1D. Regardless of the severity of diabetic retinopathy, AVR is associated with the existence of CMBs in T1D.

Microvascular disease not type 2 diabetes is associated with increased cortical porosity: A study of cortical bone microstructure and intracortical vessel characteristics

IntroductionFracture risk is elevated in type 2 diabetes (T2D) despite normal or even high bone mineral density (BMD). Microvascular disease (MVD) is a diabetic complication, but also associated with other diseases, for example chronic kidney disease. We hypothesize that increased fracture risk in T2D could be due to increased cortical porosity (Ct.Po) driven by expansion of the vascular network in MVD. The purpose of this study was to investigate associations of T2D and MVD with cortical microstructure and intracortical vessel parameters. MethodsThe study group consisted of 75 participants (38 with T2D and 37 without T2D). High-resolution peripheral quantitative CT (HR-pQCT) and dynamic contrast-enhanced MRI (DCE-MRI) of the ultra-distal tibia were performed to assess cortical bone and intracortical vessels (outcomes). MVD was defined as ≥1 manifestation including neuropathy, nephropathy, or retinopathy based on clinical exams in all participants. Adjusted means of outcomes were compared between groups with/without T2D or between participants with/without MVD in both groups using linear regression models adjusting for age, sex, BMI, and T2D as applicable. ResultsMVD was found in 21 (55 %) participants with T2D and in 9 (24 %) participants without T2D. In T2D, cortical pore diameter (Ct.Po.Dm) and diameter distribution (Ct.Po.Dm.SD) were significantly higher by 14.6 μm (3.6 %, 95 % confidence interval [CI]: 2.70, 26.5 μm, p = 0.017) and by 8.73 μm (4.8 %, CI: 0.79, 16.7 μm, p = 0.032), respectively. In MVD, but not in T2D, cortical porosity was significantly higher by 2.25 % (relative increase = 12.9 %, CI: 0.53, 3.97 %, p = 0.011) and cortical BMD (Ct.BMD) was significantly lower by −43.6 mg/cm3 (2.6 %, CI: −77.4, −9.81 mg/cm3, p = 0.012). In T2D, vessel volume and vessel diameter were significantly higher by 0.02 mm3 (13.3 %, CI: 0.004, 0.04 mm3, p = 0.017) and 15.4 μm (2.9 %, CI: 0.42, 30.4 μm, p = 0.044), respectively. In MVD, vessel density was significantly higher by 0.11 mm−3 (17.8 %, CI: 0.01, 0.21 mm−3, p = 0.033) and vessel volume and diameter were significantly lower by −0.02 mm3 (13.7 %, CI: −0.04, −0.004 mm3, p = 0.015) and − 14.6 μm (2.8 %, CI: −29.1, −0.11 μm, p = 0.048), respectively. ConclusionsThe presence of MVD, rather than T2D, was associated with increased cortical porosity. Increased porosity in MVD was coupled with a larger number of smaller vessels, which could indicate upregulation of neovascularization triggered by ischemia. It is unclear why higher variability and average diameters of pores in T2D were accompanied by larger vessels.

Retinal vessel volume reference database derived from volume-rendered optical coherence tomography angiography

Optical coherence tomography angiography (OCTA) enables three-dimensional reconstruction of the functional blood vessels in the retina. Therefore, it enables the quantification of 3D retinal vessel parameters such as surface area and vessel volume. In spite of the widespread use of OCTA, no representative volume-rendered vessel volume (VV) data are published to date. In this study, OCTA 3 × 3 mm macular cubes were processed with volume-rendering techniques to measure VV in 203 eyes from 107 healthy volunteers. Generalized linear models (GLM) were constructed to assess the impact of age, gender, visual acuity (VA), spherical equivalent (SE), and axial length (AL) on VV. Overall mean VV was 0.23 ± 0.05mm3. Age and axial length showed a negative correlation with VV. However, GLM model analysis found that AL exerted the most pronounced influence on VV. No statistically significant associations were identified between gender or between left and right eyes. This is the first study to assess 3D OCTA VV and its naturally occurring variations in a large series of healthy subjects. It offers novel insights into the characterization of normal retinal vascular anatomy in healthy individuals, contributing to a valuable reference for future research in this field.